Air supply control for air hammer



y 5, 1958 c. L. BURTON ET AL 2,842,938 AIR SUPPLY CONTROL FOR AIR HAMMERFiled Feb. 10, 1955 2 Sheets-Sheet 1 z .7; 5 i.- j

VIBRATOR 0 AIR PRESSURE TIME VIBRATOR o0 FREQUENCY TIME T; 9 5 INVENTORSHAROLD E. VAN HOESEN, CHARLES L. BURTON BY M ATTORNEY Y 15, 1958 C. L.BURTON ET AL 2,842,938

- AIR SUPPLY CONTROL FOR AIR HAMMER Filed Feb. 10, 1955 2 Sheets-Sheet 2VIBRATOR PRESSURE OR VIBRATOR FREQUENCY O TIME ACCUMULAOR O PRESSUREINVENTORS,

HAROLD E. VAN HOESEN. CHARLES Ll BURTON ATTORNEY A SUPPLY CONTRQL FGR AHAMMER Charles L. Burton, Flemington, and Harold Edward van Hoesen,Semen-ville, N. i, asslgnors to Research Corporation, New York, N. 1 acorporation of New York Application February 10, 1955, Serial No.487,376

1 Claim. (Cl. oil-=57) The present invention relates to electricalprecipitators for removing suspended material from a gas stream, andmore particularly and specifically to improved methods and apparatus forpneumatically rapping the electrodes of such precipitators to removeaccumulated deposits therefrom.

it has been discovered that it is highly desirable in precipitatorelectrode rapping operations to rap or vibrate the electrodes at varyingrates of vibration frequencies in order that more than one natural orresonant frequency or" the electrode will be attained. tion of thevibration rate through a substantial frequency range adequately agitatesall points along the length of each electrode to dislodge accumlateddeposits thereon, since each electrode will thus be vibrated at morethan one of its basic frequency harmonics.

It is a principal object of the present invention to provide pneumaticelectrode rapping apparatus which will produce vibration of theelectrodes at a multiple of their basic frequency harmonics to insureellicient removal of accumulated deposits on the electrodes.

Another object of this invention is to provide for fluid pressurerapping apparatus for precipitator electrodes which will operate toeffect a maximum of efficiency in the rapping operation with the use ofa relatively low power vibrating structure.

Still another object of this invention is the provision of electroderapping apparatus which embodies a pressure fluid accumulator and arestricted orifice arrangement by which the vibration frequencies andvibrator pressure drops are readily controlled automatically by thepredetermined size and capacity of the accumulator and orificecomponents.

Still a further object of this invention lies in the provision ofpneumatic rapping apparatus which is of extremely simple and inexpensivedesign and construction and which has a minimum of complex workingcomponents thereby insuring durability and long usage.

It is another. object of this invention to provide electrode rappingapparatus which is capable of quick and inexpensive incorporation in'substantially any presently existing pneumatic rapping assemblies.

Still further objects and advantages of this invention will becomereadily evident to those skilled in the art when the following generalstatement and description are read in the light of the accompanyingdrawings.

The nature of the present invention may be stated in general terms asincluding, in combination with a pneumatic vibrator and a source ofpressure fluid, an accumulator intermediate the vibrator and its sourceof pressure fluid, a restricted orifice intermediate the accumulator andthe source of pressure fluid controlling the rate of flow of thepressure fluid to the accumulator, and an automatically timed solenoidoperated valve intermediate the vibrator and the source of pressurefluid controlling the timed cycles of pressure fluid supply to thevibrator.

Referring now to the accompanying drawings in which Further, uniformvaria- 2842,93 Patented July 15, 1958 like numerals indicate similarparts through the several views:

Fig. 1 is a fragmentary vertical elevation, partially in schematic,illustrating one embodiment of the present in vention;

Fig. 2 is a graphic illustration of vibrator air pressures as related totime cycles incident to operation ol the apparatus disclosed in Fig. i;

Fig. 3 is a graphic illustration of vibrator frequency as related totime cycles incident to operation of the apparatus disclosed in Fig. 1;

Fig. 4 is a fragmentary vertical section, partially in schematic,illustrating a modified form of the invention disclosed in Fig. 1;

Fig. 5 is a graphic illustration of the coincidental vibrator pressuresand frequencies as related to time cycles incident to operation of theapparatus disclosed in Fig. 4; and

Fig. 6 is a graphic illustration of accumulator pressures as related totime cycles incident to operation of the apparatus disclosed in Fig. 4.

Referring to Fig. 1 of the drawings there is shown in elevation aportion of a typical installation of a pneumatic rapping mechanismembodying the basic concepts of the present invention wherein designatesthe precipitator housing or shell in which there is located a hightension electrode assembly 12 which includes a transverse high tensionframe channel member 14' supporting a plurality of electrodes 16. Thehousing or shell 19 is provided with a vertically extending insulatorhousing 13 located directly above a portion of the high tension framemember 14. The housing id contains a pressure fluid operated vibrator orrapper 29 mounted on the upper extremity of a rod 22 which passesdownwardly into the precipitatcr shell through a bearing sleeve 2d. Thesleeve is supported centrally in a disc-type insulator mounted about itsperiphery on an annular floor member secured in the lower end of thehousing 18.

The lower extremity of the rod 22 is transversely received in a tubularguite member 38 which is supported transversely of the upper ends ofchannel members 232 which in turn are rigidly supported on the upperface of the channel member 14 of the high tension frame.

Without describing in detail the construction and individual operationof the rapper 29, which maybe of any conventional and well known type,it is nevertheless apparent that the rapper 2d upon receiving compressedair or gas will actuate rod 22 causing it to reciprocate rapid- 1ystriking, with each reciprocal stroke, the upper plate on the channelmembers 32 creating vibration therein which is transmitted to the hightension frame member 14 thereby vibrating the electrodes 16 anddislcdging therefrom accumulated deposits.

In connecting the vibrator or rapper 20 to a source of pressure fluid(not shown) the upper extremity of the vibrator is connected through agastight fitting 34 a conduit 36 of insulating material or the likewhich is connected adjacent the wall of the housing 18 to an in gasket38 which is coupled to the wall and extends through to connect at itsouter extremity to a sec duit 40 which leads to and has communicationpressure fluid accumulator 42. The accumulator is connected to a secondconduit 44 communicating at a re mote point with a sauce of pressurefluid.

interposed between the remote source of pressure fluid and theaccumulator 42 is a restricted orifice do, which may contain a needlevalve construction, adapted to control the rate of flow of thecompressed material into the accumulator 42. Located between the orifice45 and the remote source of pressure fluid is a stop valve 48 which isprovided with a solenoid operator 5d operated -13 at timed cycles from asource of electric power 52 through an electric timing medium M such asa timing motor or the like.

In operation of the structure heretofore described, opening of .thesolenoid controlled valve 48 will permit flow of pressure fluid throughorifice 46 into the accumulator and up to the vibrator or rapper 2t)until the pressure is built up in the accumulator to a degreecorresponding with the starting pressure of the rapper at which timeoperation of the rapper will begin. In this construction, as isillustrated graphically in Fig. 3, the vibrator frequency will risesharply for a limited period following its initial commencement ofoperation and from this point will continue to increase gradually untilsuch time as the valve 48 is closed by the timed operation of thesolenoid 5t whereupon the vibrator will drop through a range offrequencies as the pressure in the accumulator approaches the minimumpressure for operating the vibrator.

The time period of pressure rises at the vibrator, as graphicallyillustrated in Fig. 2 of the drawings, is dependent upon the rate offlow of material through the orifice and upon the volume of theaccumulator 42, and an equilibrium pressure in the system is attainedwhen the pressure demand of the vibrator equals the supply to theaccumulator through the orifice 46.

From the foregoing and with particular reference to Fig. 3 it can beseen that the vibrator will operate through a wide range of frequenciescorresponding to a multiple of the basic frequency harmonics of theelectrodes in one cycle of operation of the apparatus as controlled bythe solenoid operated valve 48.

Referring now to Fig. 4 of the drawings there is illustrated a modifiedembodiment of the apparatus disclosed in Fig. 1 and heretofore describedwherein, in this modification, the location of the solenoid controlledvalve 48 is changed to place the valve between the ac cumulator 42 andthe vibrator 20.

Operation of the modified construction illustrated in Fig. 4 will causethe vibrator or rapper to initially commence operation at its maximumfrequency with a gradually diminishing frequency throughout its cyclingperiod of operation. The characteristics of the rapper frequency duringa single cycle of operation are graphically illustrated in Fig. 5 of thedrawings.

These foregoing characteristics of the vibrator operation are attainedby reason of the fact that during the cycle of operation when thesolenoid controlled valve 48 is closed the accumulator 42 will reach itsmaximum line pressure so that when the valve 48 is opened this maximumpressure is immediately released to the rapper which will initiallyattain its maximum frequency of vibration, Following the initial openingof the valve 48, the pressure in the accumulator will gradually diminishas will the vibrator frequency until an equilibrium is reached betweenthe pressure fluid supplied by the orifice and the demand of thevibrator. In the instance of this construction the time of pressure dropis again controlled by the size of the orifice 46 and the volume of theaccumulator 42 while the equilibrium pressure in the system iscontrolled generally by the size of the orifice 46.

Reference to Figs. 5 and 6 illustrates that operation of the apparatusillustrated in Fig. 4 of the drawings produces a corresponding andsimultaneous pressure drop in the accumulator with the frequency andpressure drop in the vibrator thus providing for a complete and accuratecontrol of the range of vibration frequencies transmitted to theelectrodes of the precipitator.

From the foregoing descriptions it is apparent that unique and usefulimprovements have been provided by the present invention which result inthe attainment of superior pneumatic operations for electricalprecipitator rapper apparatus and that the embodiments of the inventionshown are readily capable of simple and inexpensive installation asadditions to presently existing pressure fluid vibrator assemblies forobtaining in those assemblies the new and improved results inherent inthe present invention.

It is additionally apparent that the embodiments herein disclosed anddescribed are only exemplary and that various modifications of thesebasic concepts can be made by those skilled in the art in bothconstruction and arrangement without departing from the scope of thisinvention as it is defined in the appended claims. For example, whilethe rapping system has been primarily described with reference to therapping of fine wire discharge electrodes it is apparent that the systemmay be employed to vibrate other forms of discharge electrodes andcollecting electrodes.

Having thus described and explained the present invention inconstruction and operation, we claim:

A method of controlling the vibration frequencies of a pressure-fluidoperated vibrator by control of the supply of pressure fluid theretoincluding the steps of accumulating a supply of pressure fluid inadvance of the vibrator, controlling the flow of pressure fluid to theaccumulator at a rate substantially less than the demand rate of thevibrator, and periodically opening and closing communication between theaccumulator and the vibrator in timed correspondence with the attainmentand loss of vibrator operating pressure requirements in the accumulatorto cycle operation of the vibrator from maximum to minimum vibrationfrequencies within each cycle of admission of pressure fluid to thevibrator from the accumulator.

References Cited in the file of this patent UNITED STATES PATENTS1,630,482 Forbes May 31, 1927 2,699,224 Schmitz Jan. 11, 1955 FOREIGNPATENTS 458,872 Canada Aug. 9, 1949

